1. Field of the Invention
An evaporator fan controller is provided to lower energy use in a heat exchange system. More specifically, an evaporator fan controller, for initial installation or retrofit, monitors the cooling cycle of a refrigeration system and adjusts the operation of an associate fan to maximize energy efficiency.
2. Description of the Background Art
Compressor-associated refrigeration systems function by removing heat from a desired location, thereby cooling that location. For example, in a walk-in type refrigerator, often, more than 30% of the heat found in the location to be cooled is actually generated by fan motors within the refrigeration system itself. A typical walk-in refrigerator may have an evaporator coil fitted with five motors of standard configuration. If these motors are rated at a typical value of {fraction (1/20)} hp each, their combined heat output would be approximately 11,675 Btu/hr, at normal operating voltage. Clearly, if this amount of system generated heat could be reduced or minimized the efficiency of the overall cooling process would be enhanced and the refrigeration system would be less costly to operate.
Disclosed in U.S. Pat. No. 5,488,835 is a control mechanism for a refrigeration unit. The control mechanism utilizes thermostatic sensors to detect the temperature drop across an expansion valve in the refrigeration system (one sensor on each side of the expansion valve). Based on the detected temperature drop, the control mechanism then runs the evaporator fans at either a high or low speed. The drawback to this system is the inherent delay in the change in temperatures associated with the expansion valve.
A device for energy conservation in refrigeration chambers is presented in U.S. Pat. No. 5,797,276 (a continuation of ""835 cited above). This device merely claims the addition of a triac switch connected to a transformer in the ""835 system and discloses the same fan activation system based on the state of a thermostatic switch within the refrigerated chamber, a scheme not employed in the subject device.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant""s acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant""s claimed invention.
An object of the present invention is to provide an evaporator fan controller that monitors the cooling/non-cooling status of a refrigeration system as a function of detected electrical current and then adjusts the speed of an evaporator fan to an appropriate level to save energy.
Another object of the present invention is to supply an evaporator fan controller that, based on selected electrical current flow within the controlled refrigeration system, lowers the necessary energy required to operate the refrigeration system by adjusting the fan or fans associated with the evaporator coils to a lower speed when the system is in non-cooling mode and a higher speed or range of speeds when the system is in cooling mode.
A further object of the present invention is to disclose an evaporator fan controller that monitors the cooling/non-cooling status of a refrigeration system and utilizes the information collected to regulate the evaporator fan speed.
Still another object of the present invention is to relate a method of modifying a new or existing refrigeration system to produce less heat within a chamber being cooled by the system by following the cooling/non-cooling status of the refrigeration system and regulating the evaporator fan speed appropriately.
Disclosed is an evaporator fan controller that lowers energy use in a heat exchange system. The heat exchange system is usually either a walk-in freezer or a walk-in refrigerator, but may extend to other equivalent systems. Such heat exchange systems are comprised of: a cooled chamber; a compressor, generally outside the cooled chamber; a condenser, outside the cooled chamber; an evaporator, inside the cooled chamber; an evaporator fan or fans, inside the cooled chamber; and refrigerant within refrigerant carrying lines that cycle the refrigerant to the various components in the system. Also, frequently included in the refrigeration system is a solenoid that regulates the flow of refrigerant into the coils of the evaporator. Generally, the subject apparatus is an energy saving apparatus having an evaporator fan control means for monitoring a cooling/non-cooling status of the system (this is usually indicated by the on/off status of the compressor, or the solenoid), whereby the control means sets an energy saving operational speed for the evaporator fan based on the system cooling or not cooling. To accomplish this energy saving setting, a current sensor means is included. The current sensor means is coupled to the evaporator fan controller and. detects a critical current in the system that indicates if the system is cooling or not cooling (again, typically, the on/off status of the compressor or the solenoid can indicate this cooling/non-cooling status). Thus, if the cooling system is detected as on, the evaporator fan controller directs the evaporator fan to operate at a high speed (a normal operational speed or speeds that would exist without the addition of the subject invention) and if the cooling system is detected as off, the evaporator fan controller means decreases the operational speed of the evaporator fan to a low speed, thereby decreasing evaporator fan produced heat, resulting in an overall decreased energy requirement for the heat exchange system.
Further comprising the subject apparatus is air flow monitor means coupled to the evaporator fan control means, whereby if the air flow over the evaporator falls below a preset value (the decrease in air flow over the evaporator coils may be indicative of icing of the coils or obstruction by dust or dirt) the evaporator fan control means directs the evaporator fan to operate at the high speed to prevent undesirable icing of the evaporator coils.
Additionally, the subject system usually comprises a fail-safe bypass relay means coupled to the evaporator fan control means. If a power failure occurs to the energy saving apparatus the evaporator fan is directed to operate at the high speed to prevent unwanted icing of the evaporator coils in the cooled chamber.
Other objects, advantages, and novel features of the present invention will become apparent from the detailed description that follows, when considered in conjunction with the associated drawings.